Sadly, the answer is probably "both". If the network is really shoddy, it would be best to fix it. But if the files are "mission critical", then it is worth your time to use a reliable transport even if the network is solid. If three things have to break (network, TCP, plus transport) it will always be more reliable than if only one or two things need go wrong to jeopardize your system. Plus, if you don't validate your data, the kinds of errors that causes can often be really bad, much worse in some cases than something just failing outright.

I think AC has the only correct response to this post. All of the people talking about CRs must not have any experience using FTP over a spotty connection, because it is quite common to run into these kinds of issues, especially on lengthy transfers.